Fix test failures from missing DEVISE_SECRET_KEY .

If not supplied, use an empty string for `DEVISE_SECRET_KEY`. This
should only be used for tests, however; non-test environments must set
this properly to something random.
Upgrade gems in a major way, including Rails 3.2.16 .

For most gems known, lock to major instead of minor. This is because
for the last few upgrades, these have not caused any trouble in being
upgraded to the latest minors. If any of these gems cause issues in the
future, lock back to minor again.

- upgrade rails 3.2.16
- lock pg 0.17.x => 0.x
- lock less-rails 2.3.x => 2.x
- lock twitter-bootstrap-rails 2.2.x => 2.2
- lock carrierwave 0.9.x => 0.x
- lock fog 1.18.x => 1.18
- lock sidekiq 2.16.x => 2.x
- lock sass-rails 3.2.x => 3.x
- lock coffee-rails 3.2.x => 3.x
- lock therubyracer 0.12.x => 0.x
- lock uglifier 2.1.x => 2.x
- lock jquery-rails 2.2.x => 2.x
- lock rack-google-analytics 0.12.x => 0.x
- lock redis-rails 3.2.x => 3.x
Upgrade ActiveAdmin 0.5.x => 0.6.x .
Install sidekiq-spy , for development monitoring of queue.
Document § Stay Tuned, with librelist mailing list.
Build for Ruby 2.0.0,1.9.3 main, dropping 1.9.2 .

Ruby 1.9.2 is no longer supported. Build for JRuby and Rubinius for the
sake of curiosity, allowing failures.
Bump version to v1.4.3 .
Document v1.4.3 in CHANGELOG.
Merge branch 'release/v1.4.3' into stable